According to Ministry of Federal Affairs and Local Developme Aathrai has an area of 167.07 square kilometres (64.51 sq mi) and the total population of the municipality is 21747 as of Census of Nepal 2011.

[1][3] It is known widely for being the birthplace of former Nepalese Prime Minister KP Sharma Oli, Nepali Congress leader Krishna Prasad Sitaula, Communist leader Radha Krishna Mainali and journalist Tirtha Raj Niraula.

At the time of the 2011 Nepal census, Aathrai Rural Municipality had a population of 21,747.

[4] In terms of ethnicity/caste, 31.3% were Limbu, 20.0% Hill Brahmin, 11.1% Tamang, 10.8% Chhetri, 6.6% Kami, 3.7% Damai/Dholi, 3.3% Gurung, 2.9% Magar, 2.3% Newar, 2.0% Rai, 1.8% Sarki, 1.4% Gharti/Bhujel, 0.9% Sherpa, 0.8% Majhi, 0.4% Sanyasi/Dasnami, 0.4% Yakkha, 0.1% Khawas and 0.2% others.

[5] In terms of religion, 49.8% were Hindu, 31.0% Kirati, 17.5% Buddhist, 0.8% Christian, 0.6% Prakriti and 0.3% others.